Clutch device, particularly for the manual tuning control in a car radio

Abstract

A clutch device, particularly for the manual tuning control in a car radio, has the function of positively transmitting, through rack and pinion gears, movement from the tuning knob to the tuning runner. The clutch device comprises a rotating shaft (16) axially reciprocable with respect to frame (10) between an extracted position and an inserted position, with a knob (18) integral with said shaft. Shaft 16 carries a spur gear (20) at its other end, which in the inserted position of the shaft (16) with respect to frame (10) engages a gear wheel (22) integral with a pinion (24) which, cooperating with a rack (56) connected to the usual tuning runner (58) forms a rack and pinion device for positively transmitting movement. A bridge (32) having two arms (30) and (36) engages a tie bar (12), the function of which is to maintain in its operative position one of the preset keys which has been pushed in order to tune in on a station, and this occurs when said shaft ( 16) is in its inserted position; there is, furthermore, an elbow lever (44) which keeps the shaft (16) in its inserted position and is controllable through the usual slider (14) controlling the disengagement of the tuning knob clutch device.

What is claimed is: 
     
       1. A clutch device, particularly for the manual tuning control in a car radio provided with a key operated tuning memory system, in which a tie bar has the function of keeping any preset keys, pressed to tune in on a station, in its operative position, and in which a control slider for disengaging the knob tuning device has the function of disengaging the knob tuning device when a preset tuning key is operating, comprising: a rotatable shaft, axially reciprocable with respect to the frame, between an extracted position and an inserted position; a knob integral with said shaft; a spur gear integral with said shaft; a gear wheel pivoted on the frame and engaged by said spur gear in the inserted position of said shaft; a pinion integral with said gear wheel; a rack in engagement with said pinion and coupled to the usual tuning runner of the car radio; means for engaging said tie bar when said shaft is in its inserted position; and holding means for keeping said shaft in its inserted position, said holding means being releasable by said slider.   
     
     
       2. A clutch device according to claim 1, wherein said means for engagement of said tie bar comprise a bridge provided with two arms, one of which is engaged axially by said shaft, while the other is provided with an appendix which cooperates with said tie bar. 
     
     
       3. A clutch device according to calim 2, wherein said holding means comprise an elbow lever, having a first arm which cooperates with a second appendix of said bridge for keeping it in the operative position of said shaft, and a second arm which may be biased by said slider for disengagement of said bridge. 
     
     
       4. A clutch device according to claim 1, wherein a leaf spring is provided which elastically forces said rack into contact with said pinion. 
     
     
       5. A clutch device according to claim 1, wherein said gear wheel has an interruption of its teeth in coincidence with tuning range limiters. 
     
     
       6. A clutch device according to claim 5, wherein a leaf spring is provided which acts on said tuning runner as stroke limiter to aid in re-engagement of the spur gear with the teeth of the said gear wheel. 
     
     
       7. A clutch device according to claim 1, wherein the teeth of said spur gear and said gear wheel are provided with a wedge shaped profile. 
     
     
       8. A clutch device according to claim 1, wherein a brake is further provided, formed by a fork shaped spring which wraps around said shaft and is held down on the frame.